Intercommunicating system



L. D. BABROWS.

INTERCOMMUNICATING SYSTEM.

APPLICATION FILED JULY 26. I911.

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APPLICATION FILED JULY-Z6, 1917.

1,410,545. v Patented Mar. 28,1922.

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to the distant station.

station.

LEON DWIGHT MARROVJS, OF NEW YORK, N. Y.,

ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH CGMPANY, A CURPORATION OF NEW YlIfiEtK.

INTERGOMMUNICAEING SYSHEM.

Leas es.

. Application filed July 26,

To all whom it may concern 7 Be it known that I, Lnox Dwieirr ,BAR- Rows, residing at New York city, in the county of New York andxStateot New York, have invented certain Improvements in intercommunicating Systems, ofwhich the following is a specification.

This invention relates to telephone systems and more particularly to telephone s3 terns of the intercommunicating type .in which each telephone station is usually provided with lines leading to each of the other stations, suitable switching arrangement-s being also provided whereby any station may be connected to the line leading to another station or to one or more trunks common to all of the stations and leading to a distant central station.

In systems of this general character it sometimes occurs that one station of the intercommunicating system is located at a pointsomewhatdistant from the other stations so that it is impracticable or unduly expensive to carry the large number of wires necessary for full interconnnunication One of the principal objects of this invention is to provide a circuit arrangement in which the number of wires leading to the distant station of the intercommunicating system is reduced.

ln accordance with the present invention this object, together with other objects which will more fully appear from the description hereinafter given, may be secured by providing the distant station with a sin-. gle line circuit leading to each of the other stations of the system, and arranging suitable apparatus at some one of the other stations whereby an attendant at such other station may control the connection of the line circuit of the distant station with any one of the stations of the system or with the trunk or trunks leading to a distant central The system is so arranged that each of the stations may connect with the distant station direct without the intervention of the tion. Suitable supervisory apparatus is also provided whereby the attendant at the controlling station may supervise a connection established between the distant station and any other station under the control of the attendant. By means of such an arrange ment a single pair of wires leading to the Specification of Letters Patent.

attendant at the controlling sta-.

Patented Mar. 28, 1%22.

ierr. Serial no. 182,953.

distant station is suflicient to provide telephone service between said distant station aud all other stations of the system.

' The invention may now be understood from the following description taken in connection with the accompanying drawings, Figures 1 and 2 of which, when placed sid by side, constitute a circuit diagram of the invention. Referring to the drawings, stations A, B and C are shown, stations 13 and C being connected by an intercommunicating arrangement well known in the art. A number of lines, one corresponding to each of the stations of the system, are led through each of the stations such as B and G. Thus lines L, and L, correspond to stations B and C and are led through all of the stations of the system except the distant station A. One or more trunks such as T leading to a central oilice may also be provided, each of the trunks leading through all of the stations of the sytem except the distant station A. Distant station A is provided with a trunk T leadingto one of the other stations of the system such as B, at which point it is connected by means of a key K to a line L corresponding to station A and leading through all of the other stations of the system. it will be understood, of course, that while but two stations of the type of stations B and C are shown, as many other stations may be provided as conditions may require. For each additional station there would be another line of the type of lines L, and L Each of the stations of the type of stations B and (l is prov'ded with a set (it keys by means of which the stations may be interconnected, or may be connected to the trunk T leading to a distant central o'llice. Thus by depressing key K the telephone set of the station at which such key is located may be connected to the line L leading over contacts oi. key. I and trunk T to the distant station A. By depressing lreys K and K the telephone sets will be connected t lines L, and L respectively. It therefore the key K is operated at both station E and station C, the telephone sets at the two stations will be bridged across line L and the two stations will be in communication. By depressing the key K the corresponding telephone set will be connected to the trunk T leading to the central oilice. A holding key K is also provided at each station of the type of stations 13 and C fora purpose which will be described later. If there is more than one trunk T, an additional set 01 keys li and K Will be provided at each station for each additional trunk, in order to con" ectthe telephone set to any one of the tri'inks.

lit station B, in addition to the apparatus already described, arrangements are provided whereby an attendant at station B may connect station A to the trunk T or to any one of the stations in the system. Thus it it is desired to connect station A to trunk 'l the attendant at station P), by throwing the key K, may connect the trunk T, to the trunk T. It it is desired to connect station A to any other station in the system, the op erator at station B may call the other station by means of the key corresponding to such other station. hen the subscriber at such other station responds, the attendant at B will request him to operate his key li thereby connecting his set to the line L which is connected to the trunk T, leading to the station 3r, over the normal contacts ot the key K.

A ringer l is bridged across the. trunk T at station P), so that it an operator at the central oiiice desires to connect a subscriber at that oiiiccto a station of the intercommnnicat-ing system, the operator ma actuate the ringer 1. by means of ringing c irrent to call the attention of the attendant at station 13, who, by operating the key K, at said eta-- tion, may bridge the telephone set across the trunk T and ascertain the station desired. Having acquired this intormation. the oper ator at station B may then call the desired through retardation coils 4:, 5. etc.

station by depressing the key corresponding to such station. When the subscriber at that station answers. upon beingin'lbrined that call awaits him upon the trunk T, the desired subscriber may connect his set to the trunk T by depressing the trunk key K Two sources of current are provided, one source S, being for the purpose of providing signaling current for the bells at station B and C as well as other stations o'l. the tem of the same type. The source S, is also for the purpose of supplying energy to operate certain supervisory equipment whereby the attendant at station B may supervise connections from station is. Talking cur rent is supplied from a second source oi? current at a dist-ant central office over conductors 3 and through a retardation coil 2 for connections between station A and other stations of the system. T all-ring current for connections between stations Oi the type of stations B and C is supplied from the di, tant central ofiice over conductors 3 and Stations B and C are provided with bells 6 and 7 by which they may be signalled. In order to signal station A a ringing relay 8 is provided which conects ringing current to trunk T, to operate the ringer at station A, which of the standard type.

The key sets at stations of the type of stations B and C are of the Well known locking type whereby, upon depressing any key, the depressed key is locked in depressed condition, any key had been previously operated being at the same time released. Keys K K K and K are provided with one set O'ii contacts which are closed when the key partially depressed, and with additional contacts which are only closed when the key is fully depressed, the latter contacts being for si ;'nalin purposes. When the keyafter being depressed, is released, it remains locked in a partially depressed condition. Distant station A, unlike the other stations, is not provided With a key set.

With this general description in mind the invention may now be fully understood from a description of the operation. rrssumine that the. party at station B desires to call station C, the key K will be completely depressed at station B,.thereby l'n'idgrinp the telephone setof station 13 across line l over contacts 9 and 10 of key K and closinga circuit over contact 11 from the n .tive pole of source S contact 11 and spi ng 12 of key K lowerconductor 0t line L con ductor13, through hell '7, contact 1 of the switch hook, conductor :15, to the positive pole of source S The party at station C, in response to the signal thus given, will press key K, at such station, thereby bridgr ingthe telephone set'at such station across the line L over the contacts 16 and 17c? said key. The parties atstations Band (7 now have their telephone setsbridged across line L. and may communicate with each other. The signaling circuit through hell T will be broken as soonas the party at station B ceases to depress-the key K so that the key returns to its intermediate position.

The signaling circuit will also be broken when the party at station C lifts the receiver from the switch hook, thereby opening the contact 14.

If the party at station C should desire to communicate with the party at station A. the key K at-station Cayill be fully depressed, thereby bridging the telephone set across the line L over the contacts 18 and 19 of key K and closing a signaling circuitover contact 20 and spring. 21 of key K as follows: From negative pole of source S over contacts 2O andEZl, to the lower conductor of line L andthence' over conductor a d the Winding of relay 8, in parallel with the Winding and back contact of buzzer relay 2-3, over the left hand back contact of relay 24. to the positive pole of source S Relay 8 is energized over this circuit. and at its "Frontcontacts connects ringingcurrent to trunk T whereby the station A is signalled;

When the party at station A removes ceiver from' the switch hook during nonringing period supervisory relax- 25, which is in the line circuit of station 1!... will be en engized. thereby closing the circuit from negative pole of source S over the front contact of relay 2 tl'iroug'h the winding of relay 2%, to the positive pole of soiju'ce S lay 2ft is thereby energized, and at its i hand contact opens the circ of ringing relay 8, whereby said relay wl the are; at ed from again signaling station. A. Stations A and C are now in communication over the trunk T and line L which are connected over contacts 26 and 27 of key K. The function of the buzzer relay which. was energized at the same time as ringing relay 8, is to apply a non-busy tone to the line L to indicate to the calling subscriber that said line is not busy. If the line is busy the circuit of the buzzer relay will be opened at the left hand contact of relay 24L due to the encrgization of relay 25 and no tone will be heard. The non-busy tone provided by the relay 23 similar to that applied to lines L and L by the operation of ringers 6 and 7 respectively.

Assuming that the party at station C desires to obtain access to the central office over the trunk T, the key K at said station will be depressed, thereby bridging the telephone set across the trunk T, over the contacts 28 and 29 of key K The bridge thus closed across the trunk T. through the telephone set at station C, operates the line sig nal at the central othce in a Well known manner, to apprise the operator at said oiiice that a connection is desired. The connection will be completed at the central office in the usual manner.

If a call should come in over the trunk T from the central ofiice for station C, the ringer l bridged across the trunk T at station B would be actuated, thereby apprising the attendant at such station that there is a call for some station of the system. The attendant at B thereupon depresses the key K thereby bridging the telephone set at station B across the trunk T, over contacts 31 and 32. Upon ascertaining that the call is for station 0, the attendant at station B now depresses key K thereby restoring key K and disconnecting the telephone set from the trunk T, at the same time closing the following circuit: From the negative pole of source S over contact 34 of key K through the telephone set at station B. over contact 35 of F K and over conductor 36, through winding of holding relay 37 to the positive pole of source S Relay 37 is thereby energized, and at its front contact closes a holding bridge across the trunk T from point 38, through inductance 39, left hand inding of relay all, front contact of relay 3-37 contact of relav EO, to point 1. The purpose of this holding bridge is to maintain the line signal at the central otiice in operative condition after the telephone set at station B has been disconnected. The relay l0 is energized by the circuit just traced through its left hand winding, and upon pullingup its armature opens the short circuit normally closed about its right hand winding, and at its front contact closes a locking circuit for the holding bridge and the relay 40, as, follows: From point 38, through inductance 39, left hand Winding of relay l0, back contact of relay 42, front contact of relay 40, right hand winding of relay 52.0, to point 4L1. Immediately after the key It has been depressed at station B, the

attendant will fully depress the key K at station B, in order to call station C. The operation of key K releases key K but the holding bridge is locked up over the contact of relay 40 as already described, so that the release of key K with the consequent deenergization of relay 3'7, is without effect. StationC is signalled by the operation of key K in the manner already described, and upon being informed by the attendant at station B that a call is waiting upon the trunk T, the party at station G will fully depress the key K thereby bridging the telephone-setacross the trunk T, over the contacts 28 and 29 of key K and at contact 30 of said key closing a circuit as follows: From the negative pole of source 3;, over contact 30 of key K over conductor 43, and through the winding of release relay 42 to the positive pole of source S Relay 4:2 is energized over this circuit, and at its left hand contact opens the holding bridge through inductance 39 already described. whil at its right hand front contact a short circuit is closed about the right hand vvind ing of relay 4.0. Belay L0 is thereby deenergized, and its winding shunted out of the trunk circuit leading to station C, the bridge through inductance 39 being at the same time disconnected, so that a trunk circu'it extends from the central office to the station which is clear of all auxiliary apparatus. When the party at station C hangs up his receiver, the disconnect signal at the central oliice is operated in the usual mannor, and the connection may be taken down by the operator at the central office.

Assuming that a call comes in over trunk T for station A. the ringer l at station B is operatech and the attendant at station B. upon hearing the si nal, depresses key K to connect the telephone set at station B to the trunk T. Upon ascertaining that the call is for station A, the attendant at station B first depresses key K to close the holding bridge through inductance 39, and then dopresses key K thereby bridging the telephone set at station B across the line L over contacts 4% and of key K at the same time closing a circuit over coi'itact it; and spring 4t? of said key as follows: From the negative pole of source S over contacts and l-'7,lowerconductorot line L over con ductor 22, through the winding of ringing relay 8 in parallel with the winding and contact oi": buzzer relay 23, over the back left hand contact oi rela 2st to the -Jositive pole 'o'tsource S Ringing relay 8 applies signaling current to the trunk T leading' to station The attendant at station 13 also actuates the key K. thereby connecting the trunk i to trunk T over contacts .4-8 and e!) o I v the same time shitting the spring 50 said key from contact 3 contact A circuit is thereby closet from the negative pole of source S tl'iroirr'h buzzer 5: over spring 50 and contact over the hat: right hand contact oi relay 2- to the posh tire pole oi source 3 ll hcn the party at station it. in response to the signal, takes his receiver of? the switch hook. the supervisory relay 25 is energized thereby closing;- the circuit already traced through relay 2%, which at its right hand armature opens the circuit just traced through buzzer 53. to notify the attendant at station 13 that the party at station A has answered. Relay at its left hand contact, opens the circuit of ringing relay 8 and buzzer relay 2 :1. to rent further signaling or station A. Stan tion A is now connected to the cent al othce over trunk T hack contacts oi? rin ing relay 8 contacts as and sit) of he;' K and trunk T. The attendant as station E. upon noting that the buzzer has ceased to operate, fully depresses key K thereby closing contact 33 oi? said key, to actuate relay over a circuit already traced. Re 42 disconnects the bridge through inductance 89. and short circuits the winding oi relay to in a manner already described; so that the party at stationrt is able to communicate with the central oiiic'e over the trunk T. tree o1" all auxiliary apparatus. When the party at station it hangs up the receiver, supervisory relay is deenergized, opening;' the circiiiit of relay 2 which atitsback right hand contact closes the circuit previously traced through the buzzer 53. The buzzer is thereby actuated to notify the attendant at station B that the call is completed, whereupon the attendant restores key K, disconnecting trunk T tron: the trunk T and opening the buzzer circuit. i

Should the party at station A desire to obtain access to the trunk T, the receiver would be removed from the switch hook at station A, thereby actuating the supervisory relay 25 which in turn closes the circut of relay 2% already traced. Relay 2% at its front right hand contact closes a circuit from the negative pole oi'i source S through buzz- 53, contact 51 of key ll, back contact of snat station B is now connected to station it. over the line L contacts 26 and 27 of key A and the trunk T Upon ascertaining that the party at station A desires to be connected to the central oiiice. the attendant at station 13 actuates the key I, thereby connecting the trunk T to the trunlcT, over contacts t8 and 49 01 the key if; so that the line signal at the central oilice is operated in the usual manner. The actuation of key also shifts the spring 50 from contact 51 to contact The attendant at station 13 now hangs up the receiver at said tion whereupon the supervisory relay or is deenergized. and the party at station A may proceed with the all to the cef tral otlice without interruption by the attendant at staat its right hand back contact closes a oi" cuit from the negative pole oi source 5 through the buzzer ore pring50 and contact ct key K and ght hand back contact of relay it, to the positive pole oi the source l l inc actuation of thebuzzcr 53 notifies theattendant at station 13 that the call from station A is completed. whereupon the attendant restores the key K to normal, disconneetin the trunk T t'rc n the trunk T and opening the circuit of the buzzer 53.

In case thefparty at station A desires a connection. with station 0, upon removing the receiver from the switch hook the supervisory relay is energized as before, closing thc circuit of relay 24: which in turn closes a circuit for buzzer '53 as follows: From the negative pole of source S through buzzer 53, over contact 5i. back contact of supervisory relay 54;. front contact of relay 2 t. the positive pole of source S The at tendant at station E, upon hearing the buzzer, depresses key'K 'to conn tthe telephone set at said station to whereupon the supervisory relay line L embodied in what pervisory relays 25 and 54.

suits in the deenergization of supervisory relay 54, so that the buzzer circuit is again closed. The actuation of key K also closes a signalin circuit for station C over the contact 11 and spring- 1901'. said key, in a manner already described. The party at station l in response to the signal, actuates the key K thereby bridging the telephone set at such station across the line L so that stations B and C are now in communication over the line L lhe attendant at station B thereupon informs the party at station'C that a call from station d is now waiting,

whereupon the attendant at station B hangs up the receiver, and the party at station C depresses hey K, which restores key K and bridges the telephone set at station C across the line i The supervisory relay 54 is now energized, due to the closes of the bridge through the telephone set at ation C, and

the buzzer circuit is again opened, indicating to the attendant at station E that the parties at stations C and A are in communication.

At the close or the conversation between the partiesat stations A and C the parties hang up their receivers thereby deenergizing su- Relay 25 upon being deenergized opens the circuit of relay 24, thus restoring the apparatus to normal without any further attention upon the part of the attendant at station B.

It will be seen that by the arrangement above described the Various stations of an intercommunicating system may communicate with a' distant station in the usual man ner, although but a single pair or". conductors associates the distant station with the other stations of the intercommnnicating system. At the same time the distant station ma y obtain access to any of the other stations of: the system through an attendant at an intermediary station. By this arrangement it is possible in an intercommunicating sys-. tem to provide for full telephone service between all stations of the system even though one station is located at a point so remote from the other stations as to prohibit the running of the large number o1"- wires usually required in an intercommunicating system.

While the invention has been disclosed as is considered its most desirable form, it will be understood that it may be embodied in many widely different organizations without departing from the spirit of the invention.

il hat is claimed is: 1. An intercommunicating system comprising a plurality of stations of difierent types, lines corresponding to all of the stations of one type running to all stations of that type, a line corresponding to a station of a second type and running to all stations of the first type, means at each station of the first type whereby said station may be connected to any or said lines, and means at a special station of the first type whereby said station of the second type may be connected to any stati m ot the i type over a conncctim controllable from said special statiou.

fin intorconununicating system com prising a plu ity of stations or? different t pes, li es corresponding to all of the stations oi one type running to all stations of that type, a line corresponding to a station ot a second type and running to all stations oi the first type, means at each station of the first type whereby said station may be connected to any of said lines, moans at one station of tho first type whereby said station of the second type may be connected to any station or the first type, and means at said station of the firsttype controllable from other stations or that type to signal said station of the second type.

3. n intercommunicating system, com- ;nrising a plurality oi stations of different types, lines corresponding to all of the sta tions of one type running to all stations 0i that type, a line corresponding to a station of a second type and running to all stations of the first type, a central otiice, a trunk leading to said oiiice and running to all stations of: the first type, means ateach station of the first type whereby said station may be connected to anyot said lines or to said trunk, means at each station of the first type to transmit calling signals to said station of the second type, and means at one station of the first type whereby said station of the second type may be connected to any station oi the first type or to said trunk.

et. An intercommunicating system, comprising a plurality of stations of dilterent types, lines corresponding to all of the sta tions of one type running to all stations oi. that type, a line corresponding to astation of a second type and running to all stations of the first type, a central ollice, a trunk leading to said otlice and runnlng to all stations of the first type, means at each station of the first type whereby said station may be connected. to any of said lines or to said trunk, mean at one station of the first type whereby said station of the second type may be connected to any station oi the first type or to said trunk, and means at said station of the first type to signal said station of the second type, said means being controlled from any of said stations of the first type.

5. An intercommunicating system, comprising a plurality of stations of difierent types, lines corresponding to all of the stations of one type running to all stations of that type, a line corresponding to a station of a second type and running to all stations of the first type, a central ofiice, a trunk lead ing to said otlice and running to all stations of the first type, means at each station of the first type whereby said station may be connected to any of said lines or to said trunk, means at one station of the first type whereby said station ot the second type may be connected to any station otthe first type or to said trunk. means at said station. oi the first type whereby a ronnection between the station of the second type and said trunk may be. supervised. and means at each station oi the first type to transmit calling signals to said station of the second type.

6. An intercommunicating system comprising a plurality of stations of ditierent types. lines corresponding to all of the stations of one type running to all stations of that type, a line corresponding to a station of a second type and running to all stations of the first type, means at each station of the first type where y said station may be connected to any of said lines, means at a special station of the first type whereby said station of the second type may be connected to any station of the first type over a connection controllable from said special sta-- tion, and means whereby said station of the I second type may s gnal said station of the first type.

7. An intercommunicating system comprising a plurality of stations of ditl'erent types, lines corresponding to all of the stations of one type running to all stations of that type, a line corresponding to a station ot a second type and running to all stations of the first type, means at each station ot the first type whereby said station may be connected to any of said lines, means at one station of the first type \"vhereby said station or the second type may be connected to any station of the first type, means at said station of the first type controllable from other stations of that type to signal said station of the second type, and means to indicate that the line leading to said station of the second type is busy while said station is being signalled.

8. An intercominunicating system comprising a plurality of stations, a line leading from one of saidstations to a second station, an extension of said line leading to other stations of the system, a trunk leading to a central o'lfice, means whereby said line may be connected either to said extension or to saidtrunk, and means whereby any of said stations may transmit calling signals'oycr Said line leading from said first mei'itioned station.

9. Kn intercomnmnicating system com} prising a plurality of stations, a line lead ing' from one of said stations to a second station, an extension of said line leading to other stations of the system, a trunl; leading to a central o'ffice, means whereby the connection of said line to said extension or said trunk may be controlled at said second station, and means whereby any or" said stations may transmit calling signals over said line leading from said first mentioned station.

In testimony whereof, I have signed my name to this specification this 17th day of July, 1917.

LEON DlVIGHT BARROW'S. 

